1. overspeed - Noun
2. overspeed - Verb
(intransitive) To travel excessively fast or beyond the permitted rate.
(usually transitive, sometimes intransitive, chiefly mechanics) To operate an engine or machine too fast.
(India, intransitive) To speed; to drive a vehicle faster than the permitted speed limit.
overspeed (countable and uncountable, plural overspeeds)
Speed that exceeds a reasonable or permitted rate.
Unlike Otto-cycle engines, incoming air is not throttled and a diesel engine without a governor cannot have a stable idling speed and can easily overspeed, resulting in its destruction. Source: Internet
DG204/G, powered by Metrovick F.2 engines, first flew on 13 November 1943; DG204/G was lost in an accident on 4 January 1944, the cause believed to have been an engine compressor failure due to overspeed. Source: Internet